This application relates to communication between mobile units in a wireless network.
Some digital wireless communication networks use data encryption techniques to protect communications transmitted among base stations. In general, the base stations use one or more common key words, or encryption keys, to scramble the digital information passed among the base stations. These encryption keys are known only to the base stations and the people who administer the base stations. Intercepting a signal transmitted between two base stations yields no useful information without knowledge of the encryption key applied to the signal.
Unlike the base stations, mobile units in these wireless networks do not employ data encryption techniques. Therefore, intercepting a signal transmitted between a mobile unit and a base station is more likely to produce useful information than intercepting a signal transmitted between two base stations.
A wireless mobile unit includes a voice encoder circuit that receives an analog voice signal and creates digital voice data representing a user""s voice. The mobile unit receives an encryption key entered by the user, typically on the keypad or through a voice recognition circuit, and stores the encryption key in a storage device. An encryption circuit encrypts the digital voice data using the encryption key. A transmitter then modulates the encrypted voice data onto an RF signal and transmits the RF signal to a base station in a wireless network. The base station uses the same encryption key to decrypt the signal before transmitting it to another base station or mobile unit. Signals transmitted from the base station to the mobile unit are encrypted and decrypted using a user-selected encryption key in a similar manner.
Other embodiments and advantages will become apparent from the following description and from the claims.